Removed (pretty inconsistently used) tab chars from source code base.

samples/tutorial/hello.c

@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-extern const char text[];	/* In text.s */
+extern const char text[];       /* In text.s */
 
 int main (void)
 {

samples/tutorial/text.s

@@ -1,4 +1,4 @@
 
-	.export	_text
-	_text: 	.asciiz	"Hello world!"
+        .export _text
+        _text:  .asciiz "Hello world!"